1. Field of the Invention
The present invention relates generally to a single-use disposable needle-less (or needle-free) jet injection device. Particularly, this invention relates to an ergonomic jet injection device which comprises a hand-held injector having a pre-filled drug cartridge sealingly carrying injectable medication, a sealed cylinder of pressurized gas, a pre-energized discharge mechanism for penetrating the gas cylinder, and a trigger device for releasing the discharge mechanism. Features are provided which simultaneously unseal the drug cartridge and prepare the device for performing a jet injection when a user of the device changes it from a storage configuration to a use configuration. A safety feature prevents an accidental jet injection. When the user actuates the injection device, the trigger device releases the discharge mechanism to penetrate the gas cylinder, which drives a piston of the drug cartridge to effect a jet injection.
2. Related Technology
Needle-less or needle-free hypodermic jet injection devices have been in commercial use for over 40 years. A number of these devices have used pressurized gas to power a hypodermic jet injection. The related technology includes a number of teachings for gas-powered injection devices, including: U.S. Pat. No. 4,596,556, issued Jun. 24, 1986 to J. Thomas Morrow, et al.; U.S. Pat. No. 4,913,699; issued Apr. 3, 1990 to James S. Parsons; and U.S. Pat. No. 5,730,723, issued Mar. 24, 1998, to Thomas P. Castellano, et al. WIPO publication WO 97/37705 also discloses a gas powered disposable needle-less hypodermic jet injector.
The Morrow, et. al. ""556 patent is believed to teach a reusable hypodermic jet injection device in which a housing receives a shell or cartridge having a bore leading to a discharge aperture. Within the bore is received both a plunger sealingly engaging the bore, and a ressurized gas cylinder which rests against the plunger. The injection device includes a ram which has a penetrating tip confronting a penetrable wall section and seal of the gas cylinder, and a discharge mechanism for driving the ram through the penetrable wall section of the gas cylinder when a trigger device is released. Discharge of the pressurized gas from the cylinder drives the plunger to effect a jet injection, and also drives the seal of the gas cylinder to effect resetting of the discharge mechanism. The shell with its plunger, and spent gas cylinder, is discarded after an injection; and a new shell pre-filled with medication and with a new gas cylinder is used for each injection.
The Parsons ""699 patent is believed to teach a single-use jet injector which is totally discarded after one use. This injector is believed to have a body with a pair of gas chambers separated by a breakable valve. One of the gas chambers contains a pressurized gas, while the other chamber is sealingly bounded by a piston which drives a plunger. The plunger sealingly bounds a chamber into which a dose of medication is loaded by the user before the injection. This medication dose chamber leads to an injection orifice so that when the valve is broken, the piston and plunger are moved by pressurized gas communicated to the second chamber, and the plunger drives the medication forcefully out of the injection orifice to form an injection jet. After a single use, the device is discarded.
The Castellano ""723 patent, which was issued in 1998 and which does not cite the earlier Parsons ""699 patent, is believed to teach substantially the same subject matter as Parsons et al.
WIPO publication WO 97/37705 published pursuant to a Patent Cooperation Treaty (PCT) application for joint inventors Terence Weston and Pixey Thomlea, is believed to disclose a disposable hypodermic jet injector in which the device is powered by a gas pressure spring of the type common in the tool and die art as a substitute for the conventional metal spring-powered ejector pin. In the Weston device, the ram of the gas pressure spring is held in a contracted position by a trigger mechanism. When the trigger mechanism is released, the gas pressure spring is supposed to expand and drive a piston sealingly received in a bore and leading to a fine-dimension orifice in order to produce a jet hypodermic injection from liquid held in the bore ahead of the piston.
The Weston device is thought to have several deficiencies: such as difficult and costly manufacturing and sterilization processes, because pressurized gas and a drug dose need to be contained in the same package; and including a possible inability to endure long-term storage while still retaining the gas pressure in the gas spring to power an injection, and also maintaining the medication integrity. In other words, the gas pressure spring of the Weston device contains only a small quantity of gas, and depends upon the sealing relationship of the ram of this spring with a cylinder within which the ram is movably and sealingly received in order to retain this gas pressure. Even a small amount of gas leakage over time will be enough to render this injector inoperative.
In view of the above, it is desirable and is an object for this invention to provide a needle-less jet injection device which reduces the severity of or avoids one or more of the limitations of the conventional technology.
Thus, it is an object of this invention to provide a particularly ergonomic single-use, disposable, needle-free gas-powered jet injector utilizing a pressurized gas source which is hermetically sealed until the moment of injection.
Further, an object of this invention is to provide such an ergonomic gas powered jet injector in which the device has a storage configuration and a use configuration. In the storage configuration, the device is safe, with the drug cartridge sealed closed, and is incapable of effecting a jet injection. In the use configuration, the device is prepared for making a jet injection, with the drug cartridge opened in preparation for this injection.
Additionally, an object for this invention is to provide such an injection device having a multi-function component which alternatively maintains the injector in a safe storage condition, and also allows a user to place the injection device into a use condition preparatory for performing a jet injection. When the user placed the device into the use configuration, the multi-function component prepares the jet injection device by effecting unsealing of the previously sealed drug cartridge, and also removes a safety block from an obstructing position relative to a trigger of the device. Thereafter, the thumb pad trigger of the injector can be manually activated by a user of the device to perform an injection.
Accordingly, an ergonomic needle-less jet injection system embodying this invention includes, for example: an elongate generally cylindrical device body having a forward end; a drug cartridge carried at the forward end of the device body and having a cylinder in which a piston is movable to cooperatively define a variable-volume chamber holding a dose of liquid medication; a fine-dimension injection orifice in liquid flow communication with the variable-volume chamber to receive the liquid medication and discharge this medication as a high velocity forceful jet for jet injection of the medication upon forceful movement of the piston in the cylinder; a power source in the device body for forcefully moving the piston in the cylinder in response to triggering of the injection device, and a trigger assembly for initiating forceful movement of the piston, the trigger assembly including a trigger pad outwardly disposed on the device body proximate to the forward end and so configured and disposed as to be activated by a user""s thumb.
According to a further aspect this invention provides: a method of operating an ergonomic needle-less jet injection device, the device using an injection cartridge having a cylinder receiving liquid medication, an orifice in liquid-flow communication with the cartridge for forming the liquid medication into a high-velocity injection jet, a plug member in a xe2x80x9cstoragexe2x80x9d configuration of the device sealingly separating the liquid medication from the orifice, and an injection piston movable sealingly in the cylinder to displace the liquid medication via the orifice; the method including steps of: providing the device with a two-piece body having a first body portion defining a first bore into which is received a gas-power piston, and a second body portion defining a second bore into which is sealingly and movably received a hermetically sealed pressurized gas capsule; utilizing the first and second body portions and the gas-power piston to cooperatively define a variable-volume chamber; first relatively moving the first and second body portions from the xe2x80x9cstoragexe2x80x9d relative position to an xe2x80x9cinjectxe2x80x9d relative position to forcefully move the plug member from the second bore to provide for open liquid communication from the cartridge to the orifice; providing a pivotally movable thumb pad trigger which is movable from a first position radially inwardly to a second position on the body to effect triggering of the device; and providing a safety feature on the body which in a xe2x80x9csafexe2x80x9d position prevents triggering of the device.
Additional objects and advantages of this invention will appear from a reading of the following detailed description of a single exemplary preferred embodiment, taken in conjunction with the appended drawing Figures, in which the same reference numeral is used throughout the several views to indicate the same feature, or features which are analogous in structure or function.